As well known in the art, a block-type retaining wall structure formed by stacking multiple blocks is constructed in areas of terrain possessing undesirable slopes, such as an embankment, a mountainside, and the like to retain soil, thus preventing the soil from sliding and collapsing. In such a reinforced soil retaining wall, a reinforcing material for combining retaining wall blocks and backfill soil (reinforced soil mass) is generally used.
A geogrid, which is a type of reinforcing material, is in the form of a net. Recently, a strip-type reinforcing material has been used, the strip-type reinforcing material being inserted into a fitting groove formed on an upper surface of respective retaining wall blocks assembled on a front surface of the reinforced soil retaining wall, thus being installed in a zigzag pattern in backfill soil.
In other words, in order to reinforce the tensile strength of soil, a strip-type fiber reinforcing material is installed on stacked blocks. Such a fiber reinforcing material is configured such that one end thereof is secured to a block by using an anchor, an anchor pin, or the like while the other end thereof extends to be buried in soil. This results in reinforced soil mass being formed through friction generated at the interface of the reinforcing material and the soil such that the retaining wall can resist external forces such as earth pressure.
When the blocks for forming the retaining wall are supported by using such a strip-type fiber reinforcing material, one end of the strip-type fiber reinforcing material is hooked to a connecting ring protruding from a rear surface of each block, and the other end of the strip-type fiber reinforcing material having one end hooked to the connecting ring is hooked to a support bar secured to the front of a support wall spaced rearwardly of the blocks, such that the strip-type fiber reinforcing material is continuously installed in a zigzag pattern. Thereafter, reinforced soil is filled between the blocks and the support wall to form a retaining wall structure.
However, such fiber reinforcing materials are insufficient in frictional resistance against soil, and it is often necessary for the length of the reinforcing material to extend more than necessary when performing a stability examination. Although the frictional resistance can be improved by extending the length of the fiber reinforcing material, this results in backfill soil being increased in earth volume and which is disadvantageous in terms of constructability and economic efficiency.
Furthermore, in the process of installing strip-type reinforcing materials in a zigzag pattern, the strip-type reinforcing materials are changed in orientation. Due to this, when the strip-type reinforcing materials have an orientation, it is necessary to perform construction while considering the orientation of the strip-type reinforcing materials. This may lead to degradation in convenience of construction.
Furthermore, regarding as a technique for securing a fiber reinforcing material in position, there is used a technique in which the fiber reinforcing material is wound between blocks constituting a retaining wall so as to be compressed by the weight of the blocks and secured. However, if the blocks are loosened and thus a gap is defined therebetween, the fiber reinforcing material is likely to be released therethrough, leading to a reduction in passive resistance.
In an effort to overcome such disadvantages, steel, which is an inhomogeneous material, may be used as a reinforcing material. Such a steel reinforcing material has a passive resistance body provided at a rear end thereof to increase frictional resistance, which is advantageous over the fiber reinforcing material in terms of passive resistance performance due to the characteristics of the steel. However, such a metal reinforcement material made of steel or the like is disadvantageous in that material costs may be significantly increased while constructability may be relatively degraded due to provision of the passive resistance body.